The present invention is directed to methods which are generally useful in the art of water treatment, particularly the treatment of solutions and process streams and waters generated in a variety of industries. These solutions comprise any number of solids and/or liquids. Treatment of these solutions to remove solids, liquids and other contaminants is often required prior to discharge of the solutions, and is otherwise desirable for environmental, economic and commercial reasons. For example, removal is necessary for compliance with State and Federal discharge regulations, and recovered solids or liquids could be recycled.
Various industrial and other process waters and solutions can contain numerous compounds including suspended solids, colloidal particles, and/or dissolved substances. "Suspended solids" refers to mineral compounds including but not limited to sand, silt, clays, and the like or organic products such as those resulting from the decomposition of plant or animal matter, various acids, microorganisms, various hydrocarbons, including oils and greases from numerous sources. "Colloidal particles" are similar in composition to suspended solids, but generally refer to particles having a smaller size and a settling rate that is extremely slow. The term "dissolved substances" refers to cations and anions, organic matter, and various gases. The large variety of contaminants found in these industrial waste waters can pose a problem in the treatment and removal of these contaminants, in that each type of substance requires a specific treatment for removal. Quite often, the treatment for effecting removal of one form of contaminant will not be effective in removing others.
Numerous industries generate wastewater and/or process streams having solid or particulate contaminants contained therein, including but not limited to the paper processing industry, industrial laundries, the automotive and aeronautical industries, the textile industry, the steel industry, agrifood industries, petrochemicals processing, industrial finishing operations and municipal waste treatment. Paper processing streams can contain, for example, minerals such as kaolin, clay, TiO.sub.2 and CaCO.sub.3 as well as paper fines and anionic trash; waste water generated by industrial laundries can contain oils, greases, heavy metals, suspended solids such as dirt, hydrocarbon solvents, organic materials and the like. The automotive industry generates large amounts of process stream water containing, among other things, paints and solvents and more recently biomass. The solids and particulate matter can be very fine and therefore difficult to remove by conventional means.
Still other industrial activities requiring the use of process oils and water create waste streams that include mixtures of oil and water. These industries include, for example, the automotive industry, metal parts manufacturing and machining industries, steel mills, petroleum refining operations, adhesive industries, paint industries, textile manufacturing, paper industries, sewage treatment operations, and meat and food processing plants. The mixture of the oil phase and the water phase in which either phase may be dispersed in the other is known as an emulsion. The type of oil found in the emulsion and the concentration of the oil will vary depending on the industry. For example, the oils may include animal, vegetable, mineral or synthetic oil, hydrocarbons, such as tannins or greases, light hydrocarbons such as gasoline, lubricating oil, hydraulic pressure fluids, cutting oils, grinding fluids or animal processing oils. The concentration of the oil in the waste system may range, for example, from about 0.0001 to greater than 10 percent by volume. The aqueous cutting fluids or oils found in much of this waste can be problematic to treat because they are neither biodegradable nor can they be flocculated by conventional means.
The oil and water waste systems generated by industrial activity may include a wide range of various other contaminants in addition to oil. Treatment of the waste system, therefore, may include not only separation of the oil and water phases, but also removal of other contaminants. These contaminants can include various other chemicals, dirts, minerals and the like.
"Removal" as used herein refers to all manners in which one would remove suspended particles, solids, other substances and/or immiscible liquids from a liquid medium, usually water. Encompassed within the term removal, therefore, are the terms coagulation, flocculation, and separation. Although the terms coagulation and flocculation are often used interchangeably, in the present invention coagulation will be used to refer to the destabilization of colloidal particles brought about by the addition of a chemical reagent. In the same context, flocculation is then defined as the agglomeration of destabilized particles into stable aggregates called flocs, such as through use of a high molecular weight (HMW) flocculant or flocculant aid which promotes the formation of the floc. The degree of flocculation can be defined mathematically as the number of particles in a system before flocculation divided by the number of particles (flocs) after flocculation. Flocculation makes the suspension non-homogenous on a macroscopic scale. This allows the subsequent complete or partial separation of the solid or immiscible liquid phase from the bulk liquid medium using one of a number of mechanical devices. Turbidity is defined as the cloudiness or haziness of a liquid caused by finely suspended particles. Turbidity is measured using NTUs (nephelometric turbidity units). Low turbidity systems are generally systems having low solids concentrations (on a weight basis) of 0.1 or less. As a general rule, this corresponds to an approximate turbidity of 50 NTUs or less, but may vary due to the nature of the solids or dissolved colored matter. High solid suspensions include those systems containing in excess of 0.1 weight percent suspended solids, which generally corresponds to a turbidity of greater than 50 NTUs.
U.S. Pat. No. 4,001,155 discloses a paint binder for the cathodic electrocoating of electrically conductive metal surfaces comprising the reaction product of a Mannich base and an epoxide resin containing 1,2 epoxide groups. U.S. Pat. No. 4,396,732 discloses the Mannich base of an amine resin prepared by reacting a dihydric phenolic compound with a diepoxide. Neither of these reference, however, disclose the use of such resins in the treatment of solutions containing suspended particles or other contaminants.
Other Mannich-derivatized compounds are also known. For example, U.S. Pat. No. 4,952,732 relates to Mannich condensates of a substituted phenol and alkylamine containing internal alkoxy groups. The invention is reported as relating to Mannich condensates prepared by reacting formaldehyde with phenol or a phenol substituted in the ortho or para position with a hydrocarbon group and also with an alkylamine, where the alkyl group is separated from the amine group by one or more propoxy groups or by a mixture of ethoxy groups and propoxy groups. WO95/28449 discloses a polymer that is a Mannich derivative of a novolac resin. U.S. Pat. No. 4,883,826 discloses a compound prepared by alkoxylating a Mannich condensate of a phenolic compound, formaldehyde, and a mixture of diethanolamine and at least one other alkanolamine. U.S. Pat. No. 4,917,729 discloses metal chelating compounds that are Mannich derivatized bisphenol compounds, having two Mannich groups, one attached to each ring of the bisphenol. U.S. Pat. Nos. 4,795,505 and 4,792,355 relate to a similar compound having only a single phenol ring and a single Mannich substituent. None of these references disclose or suggest the use of Mannich derivatized compounds in the treatment of solutions for the removal of suspended particles or other contaminants.
Japanese Abstract 58153506 discloses a compound comprising a water soluble cationic condensation polymer of the Mannich reaction product of bisphenol, formaldehyde and dialkylamine polymerized with epihalohydrin. The compound is reported as having use as a flocculant in suspensions in rivers, for accelerating sedimentation of mud in sewage treatment plants, and for disposing oil-bearing effluent in petroleum oil refineries. The compounds disclosed in this abstract differ from those of the present invention in that a highly stable water soluble cationic flocculant is reported in the Japanese abstract, whereas the compound utilized in the present invention has both hydrophobic and hydrophilic portions in the same compound. The joint hydrophobic/hydrophilic portions of the present compounds, which can be adjusted by increasing the percent of one or the other portion as desired by the user, give the present compounds unique surface properties; the charged polyelectrolyte reported in the abstract would not have these properties.
Chem. Abstract 100:158581 discloses the Mannich derivatized phenolic byproducts obtained in the processing of wood tar; the products are taught as being useful as cationic surfactants for coagulation of rubber latexes. German Abstract No. 2333927 reports a polyacrylamide Mannich base useful as a flocculating, sedimentation, dewatering and waste water retention agent. German Abstract No. 2163246 reports the use of aminomethylated polyacrylamides as flocculating agents; the acrylamide polymer is subjected to the Mannich reaction.
There remains a very real and substantial need for methods for treating various solutions and process water and streams that contain one or more contaminants. The present invention addresses this need by providing methods for removing a variety of contaminants contained in the same or different solutions.